aerobic gram-positive bacilli part ii
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Aerobic Gram-Positive BacilliPart II
Division of Medical TechnologyCarol Larson MSEd, MT(ASCP)
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• Gram stain– Morphology– Arrangement
• Formation of spores• Catalase reaction
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Differentiation ofMajor GPR Genera
• Spore-forming GPR, catalase positive– Bacillus species– Bacillus anthracis– Bacillus cereus
• Nonspore-forming GPR, catalase positive– Listeria monocytogenes– Corynebacterium species (diphtheroids)– Corynebacterium diphtheriae– Corynebacterium jekeium
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GPR Discussed in Student Lab
• Nonspore-forming GPR, catalase negative– Gardnerella species– Erysipelothrix species– Lactobacillus species
• Branching Nocardioform GPR– Nocardia species– Streptomyces species
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GPR Discussed in This Lecture
• Two types– Short GPR– Long, filamentous
GPR• Non-sporulating
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Erysipelothrix rhusiopathiae Gram Stain
GPR, pleomorphic, Non-spore forming, Catalase negative
Erysipelothrix rhusiopathiae Colony Morphology
• Grows on BAP– Nonhemolytic or
alpha hemolytic• Microaerophilic
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GPR, pleomorphic, Non-spore forming, Catalase negative
• Catalase negative• Motility
– Nonmotile– Test-tube brush growth pattern in
semisolid motility tube at 48 hours
• H2S positive in KIA/TSI (only GPR)• Sucrose non“F”
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Erysipelothrix rhusiopathiae Identification
GPR, pleomorphic, Non-spore forming, Catalase negative
• Zoonotic– Swine erysipelas (fatal to pigs)
• Man – skin disease– Erysipelas– Direct contact with infected animal– Rarely disseminates causing septicemia
with arthritis or endocarditis
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Erysipelothrix rhusiopathiae Clinical Significance
GPR, pleomorphic, Non-spore forming, Catalase negative
What are the key biochemical reactions that identify Erysipelothrix rhusiopathiae?
Two gram stain morphologies (GPR), two colony types on SBA, catalase negative, H2S positive, test-tube brush pattern in motility tube, sucrose non“F”
• Two types– Long slender GPR in chains– Short GPCB
• Non-sporulating
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Lactobacillus speciesGram Stain
GPR, pleomorphic, Non-spore forming, Catalase negative
• Grows on BAP– Multiple colony morphologies– Nonhemolytic or alpha hemolytic
• Microaerophilic
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Lactobacillus speciesColony Morphology
GPR, pleomorphic, Non-spore forming, Catalase negative
• Catalase negative• Sucrose “F”• Vancomycin “R”
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Lactobacillus speciesIdentification
GPR, pleomorphic, Non-spore forming, Catalase negative
Lactobacillus speciesClinical Significance
• Normal flora– Mouth– GI tract– Female vaginal tract
• Rarely pathogenic– Endocarditis– Meningitis
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GPR, pleomorphic, Non-spore forming, Catalase negative
What is the clinical significance of Lactobacillus species?
It is considered normal flora of the mouth, gastrointestinal tract, and female genital tract
• Nonspore-forming GPR, catalase negative– Gardnerella species– Erysipelothrix species– Lactobacillus species
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Review
• Actinomycetes– Nocardia species– Streptomyces species
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Branching Nocardioform GPR
Nocardia speciesGram Stain
• Pleomorphic, branching, fine, delicate filaments with fragmentation GPR
• Often appears beaded
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Branching Nocardioform GPR
• Grows on SBA, Mycology media and LJ media
• Aerobic growth appears at 3-30 days
• Waxy, bumpy or velvety rugose forms, yellow to orange colonies
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Nocardia species Colony Morphology
Branching Nocardioform GPR
Nocardia species Identification
• Partially acid-fast positive• Presence of granules in specimen• Catalase
positive
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Branching Nocardioform GPR
Nocardia species Clinical Significance
• Habitat: soil and water• Mycetoma (actinomycetoma)
– Tissue swelling– Draining sinus tracts– Presence of granules
• Immunocompromised patients– Pulmonary and disseminated infections
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Branching Nocardioform GPR
What is the key characteristic in identifying Nocardia species?
Branching GPR that is partially acid fast positive
What primary disease does Nocardia cause and what 3 symptoms are seen?
Mycetoma (aka actinomycetoma). Triad of symptoms: tissue swelling, draining sinus tracts, and the presence of granules
• GPR with extensive branching, chains and spores
• Does not fragment easily
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Streptomyces speciesGram Stain
Branching Nocardioform GPR
Streptomyces species Colony Morphology
• Grows on SBA, Mycology media and LJ media
• Aerobic growth appears at 3-30 days• Waxy, bumpy or velvety
rugose forms, yellow to orange colonies
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Branching Nocardioform GPR
• Acid-fast negative
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Streptomyces species Identification
Branching Nocardioform GPR
Streptomyces species Clinical Significance
• Habitat: soil and decaying vegetation• Mycetoma (actinomycetoma)• Rarely:
– Pericarditis– Bacteremia– Brain abscess
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Branching Nocardioform GPR
How can you differentiate Streptomyces from Nocardia?
Streptomyces is acid-fast negative and Nocardia is partially acid-fast positive
• Nonspore-forming GPR, catalase negative– Gardnerella species– Erysipelothrix species– Lactobacillus species
• Branching Nocardioform GPR– Nocardia species– Streptomyces species
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Aerobic GPRSummary
Who am I?
BAP, growth at 2 days Gram Stain
Erysipelothrix rhusiopathiaeMotility Tube: “test-tube brush” pattern of growth
TSI
Who am I?
LJ agar at 1 week Gram Stain
Nocardia species
Causes Actinomycetoma
Acid Fast Stain
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